Last November, when New York City got hit with their first snowstorm, UA issued a travel waiver for NYC area airports.

I was originally booked LGA-ORD-NRT-SGN. First segment was UA. Second and third segments were NH.

I called UA to see if I could get put on an earlier flight and the agent I spoke on the phone with said her supervisor would only approve JFK-NRT-SGN all on NH.

I tried contacting United on Twitter to see if they could put me on JFK-FRA-SIN-SGN on SQ and they said they could only re-book me on their "seamless partners."

Who are your "seamless partners"?

According to UA Twitter:
1. Air China
2. Air New Zealand
3. Avianca
4. Copa
5. Ethiopian
6. EVA Air
7. Lufthansa
8. Swiss

So, I asked UA on Twitter if I could change to LGA-ORD-TPE-SGN (or JFK-TPE-SGN) on BR. They said "The changes you would like to make in your reservation are not permitted. As per Department of Transportation [regulations], the marketing carrier in an international flight must be the one who will cross or fly over the water. In your itinerary, UA will only fly the domestic routing (LGA-ORD), while it is EVA Airways who will fly over the water from ORD-TPE-SGN and that's the reason why we're unable to process the changes."

I tried asking follow up questions but by then their social media team went home for the night, so they asked me to call the 1K desk again.

I called the 1K desk and agent agreed to put me on LGA-ORD-ICN-SGN (second and third segments on OZ) the day before my originally scheduled flight.

Apparently, if UA has a codeshare flight (or a non-UA metal flight that they sell on their website), it's easier for them to make the change. That's how I was able to get them to change the ticket to LGA-ORD-ICN-SGN --because even though ORD-ICN is operated by OZ, it's a UA codeshare so UA can sell that flight. (That also explains why they were able to do JFK-NRT-SGN all on NH. Because the first segment JFK-NRT is a UA codeshare)

The day of travel, all afternoon and evening flights from LGA to ORD were cancelled because of the snow. UA agents at LGA re-booked me on BR for that same evening: JFK-TPE-SGN.

I got the flights that I initially wanted... but... now I'm confused as to who is allowed to do what in cases of weather delays and cancellations.

1. Do airport staff have more flexibility in terms of re-booking you than phone agents? They didn't give me that "D.O.T. regulation" B.S. like UA Twitter did.
2. Is there a definitive list of carriers UA will re-book you on? I thought it was UA metal is first priority, Star Alliance is second priority, and non-alliance is third priority.